Hydraulic turbine



NVENTOR BY {QMI 2 Sheet-Shat 1 L. F. MOODY HYDRAULIC TURBINE Filed Oct. 51, 1923 Nov. 6, 1928;

OR EYS 2 Sheets-Sheet A ORNEYS Nov. 6, 1928.

L.- F. MOODY HYDRAULIC TURBINE Filed Oct. 31, 1923 15 bine illustrating the invention.

Patented Nov. 6, 1928.

PATENT OFFICE.

LEWIS FERRY MOODY, or rrnnnnnnrnm, PENNSYLVANIA HYDRAULIC TURBINE.

Application tiled October 31, 1923. Serial No. 671,828.

This invention relates to hydraulic turbines and particularly to turbines 1n Wl'llCl'l the outflow from the runner is received and decelerated in a draft tube. The object of the invention is to provide a turbine which will be'simple and "inexpensive in construction and eflicient in operation.

Further objects of the invention particularly in providing a draft tube structure adapted to be suspended in position below the runner will appear from the following description and accompanying drawings in which- Fig. 1 is a vertical sectional view of a tur Fig. 2 is a vertical sectional view of a modification. a

Fig. 3 is a vertical sectional view illustrating a modification, and

29 Fig. 4 is a horizontal sectional view taken on the line 4-4 of Fig. 3.

The turbine shown in Fig. 1 is of the open flame type in which the floor 5 of the flume supports the stay vane ring 6 having inclined ,5 stay vanes 7 between the lower ring 8 and the upper bearing casting 9 containing the hearing 10 for the shaft 11 of the runner 12. The water passage through the floor 5 is provided with a liner or casting set in the concrete floor or supported in place in any desired manner. The portion of the latter below the runner 12 forms the outer wall of the turbme draft tube and is flared outwardly away from the axis continuing downward below the un- 5 der surface of the'floor 5.

Supported beneath the runner 12 and extending within the outer draft tube surface 15 is a centralconical core member 16 having its .upper end 17 with its surface formlng a o continuation of the hub of the runner 12 and flaring outwardly at its lower end 18 to a subsantially radial direction. The core 16 -is a casting of simple form and m the emv bodiment of the invention shown in Fig. 1 1t 5 is suspended by bolts 21 fastened at their upper ends to the outlet end of the casting liner 15..

The entire turbine 15 thus supported by the floor 5 of the flume permitting the flume 0 chamber and the discharge chamber to have any desired simple'form. The stay vanes 7 are inclined to a radial direction so as to impart a whirl to the entering flow and the whirling discharge from the runner 12 is re- 5 ceived a d Spread and decelerated in the au 3 (as shown in Fig. 2), of generally circular form in horizontal section for instance, this is preferably made eccentric by offsetting its center with relation to the axis of the draft tube so that the discharge from the draft tube s received and collected in a passage appro umating a volute formation accommodating the whirling lines of flow and turnin them gradually toward tail water.- a

As shown in the modification of Fig. 2 the draft tube, substantially flush with the under surfaces of the floor and curve completely into the horizontal direction where desired. Instead of being cast the draft tube sections may be built up of plate steel sections as indicated, for instance, 1n connection with the central core structure 26 of Fig. 2." Each section 27, 28, 29, 30 is generally conical in form and fits at its upper end within the section above it by an overlapping joint 32. The central core 26 is supported from the outer draft tube section 25 by the bolts 31.

In the modified form of turbine shown in Fig. 3 the intake of volute form passes the flow through the stay vane ring 41 to the ad ustable guide vanes 42 delivering it with a whlrlinto the transition space 43 under the head cover 44 directing the flow on to the runner 45; The draft tube D has its outer wall 46 formed by the surface of the concrete substructure 47 the surface 46 being smoothly curved and flared outward to merge into the horlzontal top surface 49 of the discharge chamber or plt. A circular plate 50 is suspended from the substructure 47 by stays 51 embedded inthe substructure at their upper ends and riveted or otherwise fastened to the plate 50 at their lower ends. The late 50 is spaced from the lower end of the raft tube wall 46 a sufficient distance to givethe desired deceleration to the flow passing out through the annular space between the ed e of the late and the surface of said outer Wa Angle ars 52 may be added to the under surface of the plate as strengthening and stiffening means. At its center the plate 50 carries the conical core member 53 extending upward into close proximit to the hub of the rurmer 45 so that the disc arge from the runner is annular in form between the central core and liner or casting 25 may terminate the outer wall 46. The flow, usuall discharging from the runner 45 with a w irl passes down through the draft tube and is deceleratcd thereby and discharged outward through the annular Opening at the circumference of the plate 50, the stay vanes 51 being inclined as shown in Fig. 4 in the general direction of the whirling outflow.

The draft tube structure being entirely suspended from the turbine may be installed in a discharge passage without requiring extensive form work for the concrete substructure of the power house. When desired, supporting columns or piers may be added from the bottom and cast stay vanes may be used to connectthe parts instead of the bolts 21 or plate stays 51 and the lower end of the central core 16. 26 may be covered by a horizontal plate.

The entire setting as shown in the drawings is avery simple form particularly suitable for low head installations where a small first cost is particularly important and the turbines shown in Figs. 1 and 2 are particularly adapted for use where it is possible to operate the turbine at constant load without the necessity for governing mechanism, the admission or shutting off of the flow being effected by the usual headgates.

The forming of the central core as a surface of revolution generated by a line composed of a series of straight line elements meeting each other at an angle as shown in Figs. 2 and 3 may be done without causing material hydraulic disturbances in the water passing through the tube. Ifthe outer flaring wall should be formed as a series of straight lines, the sudden changes of direction would tend to cause the flow to separate from the surface, leaving a region of eddies at each sudden change of direction. since along the outer wall there is but little pressure tending to hold the flow in contact with the surface. The centrifugal force caused by turning the flow from a vertical to a. substantially hori-' zontal direction sets up an increase of pressure along the surface of the inner core and it is therefore ossible on this inner surface to change the direction of flow more abruptly without danger of creating regions of eddies or turbulence. The simplified form of central core shown in Fi s. 2 and 3 can therefore be adopted without introducing appreciable hydraulic losses and the use of straight lines in the contour ermits the cost of the structure to be reduced: for example by simplifyin the form work if the structure should be bui t of concrete or by permitting the use of plate steel as shown in Figs. 2 and 3.

In the forms of draft tube here described, a

central core projectingupward to or near the such a void is particularly strong when the discharge from the runner contains considerable rotational components of motion about the turbine axis, as in high specific speed turbines at all loads, and in all turbines under part load or overload. When the central region of the draft tube is filled with solid material, hydraulic losses, unstable conditions or vibration are avoided, and even the use of a very simple structure such as the flat base plate of Fig. 3 becomes feasible.

I claim 1. In a vertical shaft turbine a draft tube comprising an outer member flaring outwardly to discharge the flow in a direction transverse to the axis, an inner core member displacing the flow from the central portion of the draft tube and axially extending means for entirely supporting said core member from the flared outlet end of said outer member.

2. In a vertical shaft turbine a draft tube comprising an outer member flaring outwardly to discharge the flow in a direction transverse to the axis, an inner core member displacing the flow from the central portion of the draft tube and means in the ouwardly directed portion of the tube for entirely supporting said core member from said outer member.

3. In a hydraulic turbine the combination with a turbine support having a water passage therethrough of means carried by said support and forming the outer wall of a turbine draft tube flaring outwardly toward a radial direction, and an inner core member carried by said means and flaring outwardly toward a radial direction to provide an annular flaring passage for the flow from the runner said core member being suspended from said means by connecting means in the outwardly directed portion of said passage and engaging said core member adjacent its flared outlet end, said connecting means forming the only means for suspending said core member.

4. In a turbine a draft tube comprising an outer member forming the outer surface of the tube, an inner conical core member displacing the flow from the central portion of the draft tube and comprising a plurality of late metal sect-ions secured together at their adjacent edge portions to form a continuous surface.

5. In a turbine a draft tube comprising an outer member forming theouter surface of the tube, an inner core member dis lacin the flow from the central portion of the graft tube and comprising a plurality of plate metal sections bent into generaly conical form and joined together to form a continuous surface.

6. draft tube for a hydraulic turbine comprising a member forming an outer flaring wall and an inner conical core member positioned within said outer member, one

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" rality of plate metal portions bent into gcnconlcal form and joined together.

7. A draft tube for a hydraulic turbine 7 comprising a member forming an outer flaring wall and an inner conical core member pos1t1oned within said outer member. said inner core member being formed by a pluerally conical form and joined together.

8. A draft tube for a hydraulic turbine com prising a member forming an outer flaring wall and an inner core member positioned within said outer wall, said inner core memher having a surface of revolution coaxial with the turbine generated by a line composed of a plurality of substantially straight line elements.

9. A draft tube for a hydraulic turbine comprising a member forming an outer flaring wall and an inner core member positioned within said outer wall. said inner core member having a surface of revolution coaxial with the turbine generated by a line composed of a plurality of substantially straight line elements, the elements more distant from the runner being inclined to the axis at greater angles.

10. A draft tube for a hydraulic turbine comprising a member forming an outer flaring wall and an inner core member positioned within said outer wall, said inner core member having a surface of revolution coaxial with theturbine generated by a line composed .of at least two substantially straight line elements. a

11. A draft r-tub'e for a hydraulic turbine comprising a member forming an outer flaring wall and an inner core member positioned within said outer wall, the surfaces 'of both said outer wall and of said inner core member bein surfaces of revolution coaxial with the turbine and the surface of said outer wall being generated b a curved line flaring from a substantiallyaxial to a substantially radial direction, and the surface of said inner core member being generated by a line composed of at least two substantially straight line ele' -ments, said elements meeting each other at an angle. y a

12. The comb nation in a hydraulic turbine installation comprising means forming an entrance passage or flume includin a floor The combination in a hydraulic tur-- bine installationcomprisingan entrance 'passage or fiume having a floor structure, a passage therethrough, an unshrouded propeller type runner in said passage, and inwardly extending fixed guide vanes supported from said floor structure and supporting a bearing for the shaft of said runner and providing admission means for whirlin turbine passage, whereby flui flows thereto from around and above said admission means,

said bearing having an inverted substantially conical shaped housing to which said guide vanes are attached.

bine installationcomprising means forming an entrance passage or flume including a floor structure, a contracted passage through said floor, an unshrouded ropeller type runner in the contracted portion of said passage, inwardly extendin fixed guide vanes sup ported from said oor structure above said runner and formin admission means for whirling flow to sai turbine passage, whereby fluid flows thereto from above and around said admission means, and means forming a draft tube leading from said turbine passage and having at least a portion suspended from said floor structure.

15. A draft tube for a hydraulic turbine comprising a member forming a flarin wall, and an inner flaringmme'mber positione within said other mem r, one of said members being formed by a plurality of plate metal tubular sections bent to generally flaring form and joined together, and means for supporting said tubu ar sections whereby an upper section thereof is supported by the next lower one.

. 16. The combination as set forth'in claim 13 being further characterized by the fact that said floor passage has a contracting portion with said runner disposed in the contracted side thereof, and that said guide vanes are secured to the uppermost art of said ,inverted conical housing whereby said runner and vanes are spaced apart to form a transi tion space of greater depth adjacent said housin than at the passage wall.

17. e combination in a h draulic turbine installation comprising a oor having a passage, a draft tube leading therefrom, said passage and tube forming a contracting and then expanding passage, a high s ecific speed runner disposed in the contracted of, a bearing for sup guide vanes extending inwardly from said floor to said bearing to support the latter, and spaced from said runner to form a transition, space of materially greater de th near said bearing than at the wall of said passage, said guide vanes also being transversely inclined and constituting the sole means for whirling flow to said runner.

LEWIS FERRY MOODY.

flow to said a 14. The combination in a hydraulic. tursidethereporting sa d runner, fixed 

